Tune the SQ instrument (LC/MS)

When the MS is used as a detector for a liquid chromatograph, a mass spectrum is associated with each data point in the chromatogram.

To obtain high quality, accurate mass spectra, the MS must be optimized to

Maximize sensitivity
Maintain acceptable resolution
Ensure accurate mass assignments.

Tuning is the process of adjusting MS parameters to achieve these goals.

The LC/MS has two sets of parameters that can be adjusted. One set of parameters is associated with the formation of ions. These parameters control the spray chamber (electrospray, APCI, APPI, MultiMode, or Agilent Jet Stream) and fragmentor. The other set of parameters is associated with the transmission, filtering, and detection of ions. These parameters control the skimmer(s), the octopole, the lenses, the quadrupole mass filter, and the HED electron multiplier (detector).

Tuning is primarily concerned with finding the correct settings for the parameters that control the transmission, filtering, and detection of ions. It is accomplished by introducing a calibrant into the LC/MS and generating ions. Using these ions, the tune parameters are then adjusted to achieve sensitivity, resolution, and mass assignment goals. With a few exceptions, the parameters that control ion formation are not adjusted. They are set to fixed values known to be good for generating ions from the calibrant solution.

What is the result of tuning?

The product of tuning is a tune file containing two or more collections of parameter settings: one for positive ionization and one for negative ionization, and also for Fast Scan or Ultra Fast Scan mode versions of these polarities (if available). Whenever a tune file is used, the software automatically loads the settings appropriate for the ion polarity and scan mode specified by the method. Autotune, the automated tuning algorithm, also generates a report. The tune file is stored in the MS instrument. If an MS is started on a new PC, the MS already has its tune parameters.

How are the results of tune used?

During data acquisition, the parameters associated with ion formation are controlled by the data acquisition method. The parameters associated with ion transmission are controlled by the tune file assigned to the data acquisition method.

How do I tune?

The software provides two ways to tune the LC/MS.

Autotune is an automated tuning algorithm that tunes the LC/MS for good performance over the entire mass range.

Manual Tune allows you to tune the LC/MS by adjusting one parameter at a time until the desired performance is obtained. Manual tuning is most often used when maximum sensitivity is required, when a restricted mass range is to be targeted, or when a tuning compound other than the standard calibrants is needed.

You can only manually tune if your instrument is an Agilent 61XXC. (for example, 6125C, 6135C)

Manual Tune should only be attempted by advanced users.

What do you want to do?

Run Checktune

Tune the MS automatically (LC/MS)

Tune the MS using Fast scan (LC/MS)

Run an initial autotune after installation or pumpdown (LC/MS)

Tune the MS manually (LC/MS)

Create a Dynamic Ramp table for the Fragmentor (LC/MS)

Reset Spray Chamber Parameters (LC/MS)

Calibrate gain (LC/MS)

Calculate lag factors (LC/MS)